1. Field of the Invention
The present invention relates to systems and methods for well control during oilfield operations in situations such as kicks of formation fluids, mud losses and underground blowouts.
2. Description of the Related Art
During construction or servicing of a hydrocarbon producing well, an operator can encounter a number of undesirable conditions that can pose a hazard to equipment and personnel. One undesirable condition is a “kick.” During drilling, a high pressure formation fluid can invade the well bore and displace drilling fluid from the well. The resulting pressure “kick” can lead to a well blow-out at the surface. Conventionally, during drilling, the mud weight of a drilling fluid circulated in the well is selected to provide a hydrostatic pressure that minimizes the risk and impact of a “kick.” Additionally, drilling rigs use surface blowout preventers to protect against the uncontrolled flow of fluids from a well. When activated, blowout prevention systems “shut-in” a well at the surface to seal off and to thereby exert control over the kick. A typical blowout preventer system or “stack” usually includes a number of individual blowout preventers, each being designed to seal the well bore and withstand pressure from the wellbore. Another undesirable condition is a loss of drilling fluid into a formation. That is, in some instances, the drilling fluid pumped into the wellbore is at a pressure that causes some or all of the drilling fluid to penetrate into the formation rather than flow back up to the surface. A loss is usually treated by circulating a lost circulation material (LCM) into the wellbore. The LCM usually includes particles that plug and seal the fractured or weak formation. Yet another undesirable condition is an underground blowout, which is generally understood as an undesirable subsurface cross flow between two reservoirs intersected by a wellbore. Such a cross flow can be caused when a drilling crew activates a surface blowout preventer to suppress and control a kick. The shut-in well can cause an annulus pressure increase that fractures one or more zones in an open hole region. Drilling fluid is then lost to this fractured zone. This condition can be require a combination of measures, including the use of LCM and well shut-in, to control.
The present invention provides systems and devices adapted to enhance control over the above-described undesirable conditions as well as other out-of-norm conditions.